The present invention relates generally to work boots having calked soles and in particular to such boots having replaceable metal calks.
For safety, work boots used for logging and other similar activities include numerous pointed metal calks which extend from all downwardly facing surfaces of the boot's outersole. These calks provide necessary traction for walking on logs.
It is now common practice to construct an outersole for such boots by soaking a piece of hard leather in water for a long period of time and then driving one-piece metal calks into the leather in a random array. The leather is then allowed to dry and shrink to grip the inserted portions of the calks and hold them securely and irreplaceably. This commonly used sole has numerous disadvantages.
First, suitable leather for constructing such soles is difficult to obtain and is not readily available in most parts of the world. Due to recent changes in hide production technologies, it is anticipated that this material will be in increasingly short supply and of lessening quality.
Second, the best boot sole leather is difficult to work with and cannot be readily worked without an advanced period of soaking. The insulation of calks in such leather is a costly hand operation which requires a substantial amount of manual labor.
Third, a leather sole is absorbent and will stretch if subjected to water over a long period of time. Thus, if the wearer works in or around a log pond or in a wet area of the forest, the leather can become saturated and its gripping power on the calks reduced. With the sole wet, the calks become loose and have a tendency to pull out.
Fourth, because suitable leather is a very hard material and because the calks are typically spaced in a random array, all portions of the outersole are very inflexible. When working on uneven terrain, the rigid sole forces the wearer to walk uncomfortably on the sides of his feet. Even walking on level terrain is overly difficult as there is no flexibility in the ball portion of the outer sole. As a further result, unnecessary foot ailments develop; and the boots wear down unevenly and excessively.
Fifth, because leather outer soles wear unevenly and because their calks are not replaceable, an entire sole must be replaced when only a few calks or a small area of the outersole is worn.
Sixth, the ball portion of standard calked outersoles tends to clog with mud and bark because the sole is inflexible.
Seventh, the calks driven into a leather outersole extend through the sole creating a bumpy upper surface which is an uneven platform for the wearer's foot. Extra thicknesses of insole material are required to enhance the comfort of such soles.
Eighth, the calks of standard boots resemble straight-shanked nails which are somewhat wobbly because they have no support structure suitable to maintain them perpendicular to the outersole.